1. Field of the Invention
The present invention relates to a developer supply apparatus employed in an electrophotographic system to supply a developer to a developing section provided in a processing head which subjects an electrophotographic film to various kinds of processing.
2. Description of the Related Art
One type of photographic system has heretofore been known which is capable of recording an image on a predetermined frame of a photographic film and of projecting or copying the recorded image. This type of system is disclosed in, for example, U.S. Pat. Nos. 3,528,355, 3,697,173, 3,964,828, 3,972,610 and 4,461,561.
A processing head is disposed in such photographic system to subject an electrophotographic film to various kinds of processing such as charging/exposure and development and such processing head is known from the specifications of U.S. Pat. No. 4,600,291 and U.S. patent application Ser. No. 696,590 filed Jan. 31, 1985, now U.S. Pat. No. 4,623,240.
A developing section provided in the processing head is supplied with a developer by means of a developer supply apparatus. In a typical conventional developer supply apparatus, a developer which is stored in a bottle is pumped up into a tank using a pump and then allowed to be gravitationally supplied to the developing section in the processing head by controlling a solenoid valve disposed below the tank.
The conventional developer supply apparatus suffers, however, from the following problems. Since the developer stored in the bottle must be pumped up into the tank with the pump before being supplied to the developing section, it is necessary to provide additional elements such as a tank and a pipe for providing communication between the tank and the bottle, which means that the structure of the apparatus is complicated and the production cost is raised, disadvantageously. Further, since the developer is gravitationally supplied, if there is a change in flow resistance of the flow passage due to, for example, adhesion of the toner contained in the developer to the inner wall of the pipe, it becomes difficult to accurately supply an amount of developer that is required to develop one frame on a film.